For example, in a solar cell, a transparent conductive film is formed on a transparent glass substrate made of soda lime glass etc. Irregularities are formed intentionally on the surface of this transparent conductive film in order to achieve a light trapping effect. The size of the irregularities is, for example, about 0.3 μm in relation to a film thickness of 0.8 μm. In the related art, the haze ratio is used as a feature quantity for evaluating such surface irregularities of such a transparent conductive film.
As a method for determining this haze ratio, for example, a technique disclosed in PTL 1 is known. PTL 1 discloses a method for calculating the haze ratio of a transparent conductive film by irradiating the transparent conductive film with light, dispersing the reflected light into at least two wavelengths, and computing the light intensities of these wavelengths.
In addition, PTL 1 discloses that it is possible to build a device for calculating the haze ratio into a production line for inspecting all of the solar cells having a transparent conductive film.